It carried the man who became the first human to step on the moon, Neil Armstrong, a former X-15 pilot.

VOA: special.2010.07.07

The National Osteoporosis Foundation says a test called Dual-energy X-ray absorptiometry,or DXA, is the best test for osteoporosis.

VOA: special.2010.08.31

The first plane ever to fly faster than the speed of sound was the X-1 in nineteen forty-seven.

VOA: special.2010.07.07

But he says he felt the greatest satisfaction when a thirteen-year-old painted the word "gun" and then put a big "X" through it.

VOA: special.2009.06.01

John Singer Sargent's painting known as "Madame X" was disputed when it was shown in eighteen eighty-four.

VOA: special.2010.08.04

After a few seconds, when the X-15 was safely away, the pilot started its rocket engine.

VOA: special.2010.07.07

D'Arcy plans to use the letter to embarrass Madame X's husband and destroy his political power.

VOA: special.2009.12.26

He died long before the search for Planet X resulted in the discovery of Pluto.

VOA: special.2010.07.11

They felt the X-15 could have continued to provide new information about aviation and space.

VOA: special.2010.07.07

But the story began in the nineteen forties with the X series of experimental aircraft.

VOA: special.2010.07.07

When he is clear of the B-52, he starts the X-15's rocket engine.

VOA: special.2010.07.07

From under the plane's right wing, the black sharp-nosed X-15 drops free.

VOA: special.2010.07.07

In fact, he failed to recognize Planet X in a few photographs.

VOA: special.2010.07.11

The only tragedy connected with the X-15 program happened in nineteen sixty-seven.

VOA: special.2010.07.07